House electric



F. B. FALKNOR WIRELESS RECEIVING SYSTEM 7 June 28,1927} v 11,633,932

Filed April 26. 1923 2 Sheets-Sheet l WITNESSES: INVENTOR ATTORNEY Patented June 28, 1927.

FRANK IB. FALKNOROF WILKINSBURG', PENNSYLVANIA, ASSIGNOR T0 WESTING- HOUSE ELECTRIC a 'MAnUrAor Rnve come-ANY; n'oonronn'rion or PENNSYL- VANIA.

"WIRELESS RECEIVING sYsTEM'.

My invention relates to radio receiving systems and-particularly to devices for use in connection with regenerativereceivers.

Broadly speaking, the object of my invention is to improve the-reception ofradio signals and to reduce Y interferences between adjacentradio receiving stations.

More specifically, the objects of my invention are to provide mea-ns whereby. damped or spark'sig'nals may be received on a super-regenerative receiver, thereby obtaining' the advantages of super-regenerative reception for spark; signals, as Welles forcontinuous wave signals.

A further object is to provide 'means whereby the re-radiation ordinarily experienced when such super-regenerative receivers are connected*to-an-aerial may be greatly reduced,rcduced specificallyto a point where-its'strength is not such-as to'cause it to'be received by another adjacent receiving station with suflicient intensity to interferc-witlrithe reception of signals by the sec on'd station, 'Whetherthe signals desired by the secondstatiomareon the same or'ona different 'wave length as those received 7 by the super-regenerative receiver."

In carrying my invention -into effect, I provide ;-means =vvhereby -.thedamped spark signal waves may be convertedinto signal waves which .areequivalent to undamped waves, modulated at spark' frequency, such modulated undamped waves a being suitable for 1 reception; byrthe super-regenerative receiver, whichis not the case with damped spark-signals. Idothis by :a meanswhich also isolates theaerial-from direct connection with the receiver insuch away that the energy of the iincomingfsign als to -which the I aerial is tuned, -.-is readily transferred from said aerial through c an intermediate system of circuits to the supenregenerative receiver. .-At the same time, the characteristic of the i ntermedia-te: transfer circuit is such. th at the transfer' of energy from 1 the super-regenerative receiver to the aerial takes place with much 'more difficulty? that is, the transfer 11 11821118 between the aerial and the receiver are adapted to transferenergy in one Tlirecl'tion only from aerial-to-receiver. A study of the super regenerative methods of radio reception: by umany others in the art has shown thatnsuper regenerative reception is successful and' desirable on undamped signals, -modulate-dvor not, a as, may be I the Application filed. April 26, 1923. Serial No. 634,727.

case, but that reception of damped-spark sigati ve receiver are concerned, modulated undamped wave signals, although the undamped wave is'probably present in :the transfer circuit tothe super-regenerative receiver only during theperiods during which the damped wave'trains are being received bvthetaerial. v

* Investigators in; the 'art'ha-ve noticed the fact that when -21super'-regenerative receiver is directly connected to the aerial or is in direct-inductive 'relationship with the aerial and blankout the signals they desire to receiveandthis fact tends to limit the usefulness of this type of regenerative receiver. My invention reduces this interference by interposing between theaerial-and the regenerative receiver circuits, other circuits which do not oscillate freely at the reception frequency and which also produce a much lower Avavc frequency to supply totheregenerativero eiver. therebyallowingthe aerial to be tuned to the frequency of the desired signals and requiring that all of the other circuits in the-combination be tuned toa wide- 1y different frequency. Thiscausesall of the local: oscillating circuits which are supplied 'WlthvlOCfllpower to oscillate at the samefrequeney which is' widely different from that of the aerial. The fact that the frequency "of the aerial then :is-so much different from the frcouencyot the oscillations in'other circuits of the set results in substantlally reducing the amount of OSCIllZLtOIY energy, at

this different frequency, given to the aerial.

This is due to the fact that the aerial does not oscillate easilyat a frequency to which it is not tuned and therefore a minimum amount of energy is accepted by it and retion, and

Fig. 2 is a diagrammatic view of curves illustrating the relation of the various frequencics involved in my invention.

Figure 1 illustrates a typicalcircuit combination suitable for practicing my invention, consisting of an aerial or other radio receptor circuit 1, a condenser 2, a radio fre' quency inductance 3, a ground 4, a grid leak and grid condenser 5, a triode valve 6, a high voltage battery 7 and a radio frequency output inductance 8. A heterodyne driver 9, consisting of a triode bulb and its oscillatory circuits comprises part of my device, its function being to supply energy at a suitable frequency to the aerial circuits through a radio frequency coupling transformer 11.

A typical regenerative receiver 20 as outlined in Patent No. 1,424,065 to E. H. Armstrong comprises a further portion of my in vention. This may consist, as shown, of a triode valve '21, a high voltage battery 22, inductor coils 23 and 24 and condensers 25 and 26 for producing the variation frequency and variometer 27 in the plate circuit, inductively coupled to coil 12. Triode 31 serves as the final stage of amplification and detection, andsupplies the phones 32.

A radio frequency inductance 12 forms the input coil for the super-regenerative receiver and another radio frequency inductance 13 acts as a feedback coupling or tickler. The regenerative receiver may be one of thetypical regenerative circuits as outlined in said patent or may be one of the possible modifications which operate in a similar way.

The condenser 2 serves to tune the aerial circuit as a whole to-the desired incoming waves, which in the instance under consideration may be damped spark signals. These signals set the aerial into oscillation and their oscillations react with the oscillations developed in the heterodyne driver 9, giving a beat note frequency or resultant, which i s dependent in frequency on the mutual frequency of the signal and the heterodyne oscillations. The frequency of the heterodyne driver is adjusted to such value that the resulting beat note occurs at a suitable radio frequency. This beat note frequency is then applied to the grid circuit 15 of the rectifier triode 6 and is there rectified to give a radio frequency comptmcntat the frequency of the beat note. This,'in effect, is an undamped wave, nodulated by spark signals, withportionsof the wave train cut ting up of the undamper wave trains into trains of the length and spacing corremponding to the damped spark signals received. This modulated undamped signal is then transferred through the radio frequency in duct-ances 8 and 12, which together form a radio frequency amplifying transformer .14 of high selectivity and sharp tuning, into the circuits of the. regenerative receiver, where they are amplified aud'detecte'd by the operations which are characteristic of the super-regenerative receivers.

Figure 2 con ains a series of curves illustrating the character and relation of the various waves and frequencies concerned in the various circuits of. my device during its operations. Curves 21 and 22 show two trainsof waves corresponding to damped spark signals. Curve shows the continuous wave produced by the heterodyne driver. Curves 24 and 25 showthe' resultant beat frequency produced by the interaction between the damped sparksign'als 21 and 22 and the heterodyne driveroutput 23, Curves 26 and 27 show the character of the rectified wave output from the plate circuit of "the rectifier triode 6. Curves 28 and 29 show the character of the signals transferred to the regenerative receiver after the direct current component has been removed by the radio frequency transformer.

In the typical circuit for practicing my in-- vention damped or spark signals may be received at a frequency corresponding to the wave length'of, say 3 60 meters. The hetero dvne driver may then be adjusted to such frequency that the resultant beat note period corresponds to thefre'quency of 3000 meter signal wave length i. e., 100,000 cycles, which is convenient for reception. This resultant beat note is then 'rectifiedso as'to produce the desired 3000 meter modulated undamped wave which is then fed into the regenerative receiver. The receiver then has in its oscillatory circuits oscillations at frequency approximately that of the 3000 meter wave. This frequency is sufiiciently different in period from the frequencyto which the aerial is tuned to make the aerial very poorly responsive to it. I V

Likewise, the heterodyne driver 9 is tuned to a substantially different frequency than that of the aerial so the aerial is poorly responsive to it.

Furthermore, the limited amount of capacity between the elements of the triodevalve interposes a considerable CTI Ill!

impedance to the transfer of energy from coil 8 through the intermediate circuitsto the aerial. This is the condition of unilateral'energy transfer, as before suggested. For this reason, little energy comes to the aerial by way of coil 8 from coil 13 even though both coils may be in close inductive relationship. These are the facts accounting for the limited transfer of local oscillatory energy from the regenerative receiver to the aerial and its reduced re-radiation from the aerial.

In practice, I have. been able by means of this and similar circuits to obtain satisfactory reception of spark signals on the super-regenerative type of circuit. I find that, when the super-regenerative circuit is used with the circuits of my invention, the reception of spark signals is as satisfactory as is the reception of undamped signals on the same circuit and I further find that the presence of my circuits reduces the re-radiation' which is characteristic of these superregenerative circuits to the point where troublesome interferences is not caused for nearby receiving stations.

Vhile I have shown only one embodiment of my invention in the accompanying drawing, it is capable of various changes and modifications without departing from the spirit thereof and it is desired, therefore,

that only such limitations shall be imposed thereon as are indicated in the prior art or in the appended claims.

I claim as my invention:

1. A radio receiving system comprising a radio receptor circuit, a heterodyne generator and a beat-resolving means cooperating therewith, and a super-regenerative detector operatively associated with the output of said beat-resolving means.

2. A radio receiving system comprising an aerial circuit, a circuit for heterodyning incoming spark signals to a resultant beat note of a different frequency than that of inco1n- 'ing signals received by said aerial, a circuit for rectifying said het-erodyned signals to a modulated continuous wave at the heterodyned frequency, and a super-regenerative detector circuit for receiving and detecting said modulated continuous wave.

3. A radio. receiving system, suitable for damped wave reception on a super-regenerative'receiver, comprising an aerial or other radio receptor circuit, a heterodyne driver circuit, a detector circuit and a super-regenerative circuit operatively associated with the output of said detector.

In testimony whereof, I have hereunto subscribed my name this 23rd day of April,

FRANK B. FALKNOR. 

